1. Field of the Invention
The present invention relates to a method of producing xylylenediamine by the hydrogenation of dicyanobenzene. Xylylenediamines are useful as the material for polyamide resins, hardeners, etc. and the intermediate material for isocyanate resins, etc.
2. Description of the Prior Art
Various methods have been proposed for the production of xylylenediamine by the liquid-phase hydrogenation of dicyanobenzene in the presence of a catalyst. For example, Patent Document 1 describes a batch-wise hydrogenation of phthalonitrile into the corresponding xylylenediamine using an autoclave in an alcohol solvent in the presence of Raney nickel or Raney cobalt together with a small amount of a caustic alkali. Patent Document 2 describes a catalytic reduction of phthalonitrile with hydrogen in liquid phase in the presence of a nickel-copper-molybdenum-containing catalyst. In the working examples, the catalytic reduction is carried out by a fixed bed continuous hydrogenation.
Patent Document 3 describes a production method of m-xylylenediamine in which impurities having a boiling point higher than that of isophthalonitrile are removed from the isophthalonitrile obtained by the ammoxidation of m-xylene in the first distillation step, the organic solvent is removed in the second distillation step, and isophthalonitrile from the column bottom is added with a specific solvent and liquid ammonia and then hydrogenated. Patent Document 4 describes a production method of xylylenediamine, which comprises contacting the ammoxidation gas of xylene directly with an organic solvent or with molten phthalonitrile, removing components having a boiling point lower than that of phthalonitrile from the resulting solution in an organic solvent, suspension or phthalonitrile melt, removing components having a boiling point higher than that of phthalonitrile before the hydrogenation.
Patent Document 5 teaches that xylylenediamine is obtained in a high yield and the catalyst life is prolonged by conducting the hydrogenation of phthalonitrile while controlling the concentration of benzamide, benzoic acid and their related compounds (impurities having a boiling point higher than that of phthalonitrile) in the hydrogenation liquid at a specific level or lower by distilling off benzamide, benzoic acid and their related compounds.
Patent Document 6 describes a production method of xylylenediamine in which the ammoxidation gas of xylene is contacted with an organic solvent and then the resulting solution is added with liquid ammonia and the hydrogenation is conducted without separating the phthalonitrile absorbed in the organic solvent. Patent Document 7 describes a production method of xylylenediamine, which comprises contacting the ammoxidation gas of xylene directly with an organic solvent or with molten phthalonitrile, removing components having a boiling point lower than that of phthalonitrile from the resulting solution in the organic solvent, suspension or phthalonitrile melt, and conducting the hydrogenation without removing the component having a boiling point of higher than that of phthalonitrile.    Patent Document 1: JP 38-8719B    Patent Document 2: JP 53-20969B    Patent Document 3: JP 2003-26639A    Patent Document 4: JP 2007-505068A    Patent Document 5: JP 2004-35427A    Patent Document 6: JP 2002-105035A    Patent Document 7: JP 2007-505067A
Dicyanobenzene is produced by a known ammoxidation of dialkylbenzene such as xylene, for example, by a method described in Patent Documents 8 to 15.    Patent Document 8: JP 49-45860B    Patent Document 9: JP 49-13141A    Patent Document 10: JP 63-190646A    Patent Document 11: JP 1-275551A    Patent Document 12: JP 5-170724A    Patent Document 13: JP 9-71561A    Patent Document 14: JP 11-246506A    Patent Document 15: JP 2003-267942A